Piezo-electric fuze



y 1962 T. DE w. DOWDELL ETAL 3,031,968

PIEZO-ELECTRIC FUZE Filed April 9, 1958 United States Patent Office.

3,031,968 Patented May 1, 1962 3,031,968 PIEZO-ELECTRIC FUZE Thomas de W. Dowdell, (Ireland, Pa., and C Walton Musser, Beverly, Mass., assignors to the United States being completed through the inner ogive 12 and the of America as represented by the Secretary of the Army Filed Apr. 9, 1958, Ser. No. 727,501 3 Claims. (Cl.102--70.2) (Granted under Title 35, US. Code (1952), sec. 266) The invention described herein may be manufactured and used by or for the Government for governmental purposes without the payment of any royalty thereon.

This invention relates to piezo-electric fuzes such as are used to fire the charge of a projectile, and more particularly to a piezo-electric fuze wherein the piezo-electric crystal is so mounted as to ensure uniform and reliable operation of the fuze.

' In spite of the fact that the instantaneous response of a piezo-electric crystal makes its use as a means of firing the charge of a projectile highly desirable, past attempts to make such use of it have not been altogether satisfactory. This is largely due to the lack of a crystal mounting which insures uniform and reliable operation of the fuze and to the difficulty of effectively interconnecting the crystal with the detonator at the base of the projectile.

The present invention avoids these difliculties by the provision of an improved mount which properly and securely supports the crystal and seals it in a compact unitary assembly so that storage under various atmospheric conditions does not result in any marked deterioration of the unit.

The invention will be better understood from the following description considered in connection with the accompanying drawings.

Referring to the drawings:

FIG. 1 is a sectional view of the ogive of a projectile which embodies a preferred form of the invention, and

FIG. 2 is a wiring diagram of the piezo-electric fuze.

FIG. 1 illustrates a mount including a conductive housing which engages one side of a crystal 11 and extends into an opening in the forward end of an inner ogive 12. A conductive member 13 engages the opposite side of the crystal and also extends into the same opening. Between the housing and the member 13 is interposed an insulator 14. The conductive member 13' has substantially the same diameter as the crystal as shown in FIG. 1, to support the crystal during firing. It has a T shape to extend beyond the container 10 to allow for connection to the lead 18. The insulator 14 is cup-shaped and surrounds only a portion of the crystal 11, allowing the forward face of the crystal 11 to be in contact with the container 10. The insulator generally matches the contour of the conductive member 13 within the container 10 and along a portion of the length of the T. The container 10 has substantially uniform wall thickness, is in contact with the forward face of the crystal, and, as illustrated in FIG. 1 has parallel walls in contact with the insulator 14, extending inwardly toward its longitudinal axis in contact with the insulator 14 to a diameter less than the diameter of the conductive member, thereby supporting the insulator and the conductive member, then extending along its longitudinal axis for substantially the full length of the insulator 14. This mount is surrounded by a rubber cup 15 which fits within the outer ogive 16 of the projectile, and holds the conductive housing 10 in contact with the inner ogive 12.

The crystal 11 is interconnected with a detonator 17 in the base of the projectile as indicated by the wiring diagram of FIG. 2, the lead 18 of FIGS. 1 and 2 being connected to one side of the detonator and the circuit housing 10.

In the operation of the above described piezo-electric fuze, the crystal is pressurized by the projectile striking a target. This generates an electric current which sets off the explosive detonating charge. Since the transmission of this current is substantially instantaneous, crushing of the projectile is minimized. A fuze of this type also may be made highly sensitive so that it may be set off by contact with an object offering relatively little resistance to the projectile.

Vile claim:

1. In a projectile of a type using a piezo electric fuze for firing an explosive charge, said projectile having an outer ogive, an inner ogive and a detonator activated by said piezo electric fuze, the combination therewith of the improvement whereby more uniform and reliable operation of the fuze is obtained after storage under various atmospheric conditions, said improvement comprising: a compact unitary piezo electric fuze consisting of: a piezo electric crystal, a conductive member having a forward portion in contact with a rear face of said crystal and having substantially the same diameter as the crystal and a rearwardly extending portion of reduced diameter, an insulating material in the form of a cup surrounding a portion of said crystal, surrounding all of the forward peripheral portion of said conductive member and said insulating material having a reduced diameter surrounding a portion of the rearwardly extending portion of said con-' ductive member, and a conductive housing in contact with a forward face of said crystal, extending around and parallel to the sides of said crystal, said conductive housing also extending around said conductive member and said insulating material, said conductive housing having substantially uniform wall thickness in rear of said crystal and matching the contour of and in intimate contact with said insulating material and having a rearwardly extending portion for a length of said insulating material; a lead, one end of which is connected to said rearwardly'extending portion of said conductive member and another end of which is connected to said detonator; and said inner ogive having an opening in its forward end with the side wall of said opening being adapted to electrically contact and receive said rearwardly extending portion of said conductive housing.

2. A projectile according to claim 1 in which a rubber cup is fitted within said outer ogive, said rubber cup being in intimate contact with said conductive housing and said inner ogive whereby said conductive housing is held in contact with said inner ogive.

3. A unitary piezo electric fuze consisting of: a piezo electric crystal; a conductive member having a forward portion in contact with a rear face of said crystal and a rearwardly extending portion of reduced diameter, said forward portion having substantially the same diameter as said crystal; an insulating material in the form of a cup surrounding a portion of said crystal, surrounding all of the forward peripheral portion of said conductive member and said insulating member having a portion of reduced diameter extending rearwardly over a portion of said rearwardly extending conductive member; and a conductive housing of substantially uniform thickness in rear of and in contact with a forward face of said crystal, extending around and generally parallel to the peripheral sides of said crystal, parallel to said conductive member and said insulating material, being in intimate contact with said insulating material, generally matching the contour of said insulating material and extending for sub stantially a major part of the rearwardly extending portion of said insulating material.

(References on following page) 4 \3 References Cited in the file of this patent 2,849,957 Kuller et a1 Sept. 2, 1958 2,871,787 Rizer et a1. Feb. 3, 1959 UNITED STATES PATENTS 2,892,411 Brown et a1. June 30, 1959 a 2,764,091 Hudson Sept. 25, 1956- 5 2934661 Ch mbers Apr 2,793,260 Ciosek May 21, 1957 FOREIGN PATENTS 2,834,952 Harris May 13, 1958 740,195 Great Britain Nov. 9, 1955 

